Download The Atmosphere and air pollution

THE ATMOSPHERE AND
AIR POLLUTION
LAYERS OF THE ATMOSPHERE
• Lower atmosphere – contains
99% of all atmospheric air
• Troposphere
• Stratosphere
• Ionosphere
• Mesosphere
• Thermosphere
• Exosphere
TROPOSPHERE
• Layer where we live
• Most of the O2
• Extends to 5-9 miles from the Earth’s
surface at sea level
• Most weather occurs here
• Most dense layer of the atmosphere
STRATOSPHERE
• Directly above the troposphere
• Extends from 9 to 31 miles above the Earth at sea level
• The Ozone Layer that traps and scatters UV radiation from the sun occurs
here
• Drier, less dense air than that found in the troposphere
IONOSPHERE
• Mesosphere
• Directly above the
stratosphere 31-53 miles above
the Earth’s surface at sea level
• Thermosphere
• Directly above the
mesosphere 53-372 miles
above the Earth’s surface
EXOSPHERE
• Outermost layer of the Earth’s atmosphere
• Transition zone between the Earth’s atmosphere and outer space
• Lowest atmospheric pressure of all the layers
COMPOSITION OF EARTH’S
ATMOSPHERE
• 78% Nitrogen!!!!
• 21% O2
• 0-7% water vapor (H2O) – varies by
climate
• 0.01-0.1% carbon dioxide (CO2) –
varies by location
• 0-0.01% Ozone (O3) – varies by
location
ATMOSPHERIC INVERSION
• Natural temperature gradient of lower atmospheric
air is reversed
• Usually warm air closest to Earth and gets cooler as
move away from Earth (convection currents)
• When dense cool air gets trapped under a layer of less
dense warm air, the air becomes more still and
upward air currents are prevented from developing
• Air pollution can get trapped and build up to harmful
levels
• Common in large cities surrounded by hills and
mountains
•
•
•
•
Mumbai, India
Mexico City, Mexico
Los Angeles
Vancouver, British Columbia
WHY DOES IT RAIN?
• Convection
• Warm air rises – less dense than
cool air
• As warm air rises, it loses heat and
cools
• Warm air has a higher capacity for
holding water vapor
• As warm air rises, water vapor
condenses
FRONTS
• Warm Fronts
• Warmer air moves into an area of cooler air
• As warm air rises, get drizzly rain
• Adds heat to cooler air and temperature and humidity near the ground increase
• Cold Fronts
• Cold air moves in and pushes warm air upwards
• Humidity in air condenses rapidly and falls as precipitation
• Usually associated with a line of rain showers and thunderstorms
CONVECTION CELL MODEL OF
ATMOSPHERIC CIRCULATION
• Hadley Cells
• Coriolis Effect
OCEAN INTERACTIONS
• Convection currents
• Cool dense water from poles sinks and moves towards equator
• Warmer, less dense water rises and floats toward the poles
• Ocean currents transport a lot of Earth’s heat
EL NINO SOUTHERN OSCILLATION
(ENSO)
• A climate shift in tropical equatorial Pacific Ocean
• Occurs every 3-7 years and can last a few months to up to 4 years
• Occur when trade winds that normally blow east to west reverse
• Surface waters become warmer
• Nutrient rich upwellings near Peru are suppressed – fish pops decrease
• Can effect worldwide weather patterns
EFFECTS OF EL NINO (1)
• Northern US, Canada, Brazil, Indonesia, Australia, India, Southeast Africa
•
•
•
•
Less snow (snow fed rivers will decrease in spring because of lack of snow melt)
Drought
Wildfires
Increase in diseases
• Malaria and dengue fever
• Cholera and othe water borne issue
EFFECTS OF EL NINO (2)
• Southern US, Cuba, northern Peru, Ecuador, Bolivia, east Africa
• Suppression of hurricanes in Caribbean and Atlantic Ocean
• Increased flooding and landslides
• Increased diseases from contaminated water
AIR POLLUTION
• Anything added to the atmosphere that can cause harm to life
• Point source
• Single, stationary source – smokestacks, methane from landfills, smoke and ash
from forest fires
• Non-point source
• Dispersed or mobile sources
Air pollutants are found throughout the entire
global system. Air Pollution is the 5th largest
killer in India.
China, India, Africa
WHY DO WE CARE? (HUMANS)
• We inhale 20,000 liters of air each day
• Causes 150,000 premature deaths in the world each
year (53,000 in U.S.); aggravates other diseases
• U.S. human health costs from outdoor air pollution
range from $40 to $50 billion per year (CDC)
• Health impacts
- acute – pollutants bring on life-threatening
reactions w/in a period of hours or days; causes
headache, nausea, irritation
- Chronic – pollutants cause gradual deterioration of
health over years and low exposure, asthma, allergies,
low energy, etc
- Carcinogenic – pollutions that causes cancer e.g.
benzene
- Expansive  settles in water ways, bioaccumulation in
food chain, effects our nearby ecosystems
WHY DO WE CARE? (NOT HUMAN)
• Damage to Plants
- Agriculture – crops loss ~$5
billion/year
- Forests – significant damage
to Jeffrey and Ponderosa Pine
along Sierra Nevada; tree growth
declined 75% in San Bernardino
Mountains
- suspected to increase plant
diseases and pests
• Damages buildings, bridges,
statues, books
• Aesthetics: It looks ugly. We all try
to avoid living in polluted areas
(admit it…)
LIST OF AIR POLLUTANTS TO KNOW
•NOX general form refering to N2O (nitrous oxide), NO2
(nitrogen dioxide), N2O4 (dinitrogen tetroxide), etc.
•SOX general form referring to SO2 (sulfur dioxide) and SO3
•CO2 and CO
•Acidic biproducts forming acid rain and dry deposits: H2SO4
(sulfuric acid), HNO3 (nitric acid), HC2H3O2 (acetic acid)
•Tropospheric ozone O3
•Particulate matter (ash, dust, combustion of gas or diesel black
smoke)
CO
•
•
•
Prevents O2 from
attaching to
hemoglobin in
blood.
Odorless, Colorless,
It is created by
incomplete
combustion of gas
and is found in car
emissions
Particulate Matter (PM)
PM ranges in size from
.01μm to PM10.
PM2.5, is of great
concern, because nose
hair does not filter it out
and it can become
embedded in the lungs.
Asbestos.
PM can also scatter light.
Particulate Matter
PM can create what is called a haze or smog.
AMAZON HAS HAZE FROM SLASH
AND BURNING OF RAINFOREST
Major Air Pollutants
•
Volatile organic compounds (VOC)
•
Ozone in troposphere
•
Lead
•
Mercury
Sulfates are considered to be secondary pollutants
because they are transformed from primary pollutants.
Gas can become a VOC because it evaporates at
room temperature, leaving a strong smell, is a
hydrocarbon that can leave PM,
The combustion of coal is the primary cause of
mercury in the air.
Dry cleaner fluid, spilled gas lighter fluid are additional
VOC.
Primary Pollutants
•
Primary pollutants: polluting
compounds coming directly out of
smoke-stacks, exhaust pipes, or
natural emission source
•
E.g., CO, CO2, SO2, NOx, and most
suspended particulate matter
Secondary Pollutants
•
Secondary pollutants: pollutants
transformed in the presence of sunlight,
water, oxygen or other compounds
•
E.g., ozone, sulfate, and nitrate
Air pollution comes from
both natural and human
sources.
Natural Sources of Air
Pollution
•
Volcanoes
•
Lightning
•
Forest fires
•
Plants
Anthropogenic Sources of Air
Pollution
Anthropogenic: From the Greek,
•
Anthropos, “human”
•
-genesis, “created”
•
Meaning anything caused or created
by human activity
Anthropogenic Sources of Air
Pollution
•
On-road vehicles
•
Power plants
•
Industrial
processes
•
Waste disposal
Photochemical smog is still
an environmental problem
in the United States.
Smog Formation
California smog is mostly due to ozone and called brown
smog. London has SO2 smog and is called tea and
crumpets smog. Ok, I made that up, it is gray smog.
•
Smog forms when sunlight, nitrogen
oxides (NOx), and volatile organic
compounds (VOCs) are present.
Smog Formation
•
The secondary pollutant ozone is a
major component of photochemical
smog.
•
Sulfur is the main ingredient in
sulfurous smog.
INDUSTRIAL SMOG
Beijing in March 2012
• The U.S. had its own “killer smog” from industrial pollution.
Shown is Donora, Pennsylvania, in 1948, at mid-day.
Subsequent demand for legislation against pollution
made U.S. air much cleaner.
INDUSTRIAL SMOG
• Chemistry of industrial
smog:
• • Burning sulfur-rich oil or
coal creates SO2, SO3,
sulfuric acid, ammonium
sulfate.
• • Carbon leads to CO2
and CO.
Photochemical Smog
•Photochemical
smog
CHEMISTRY OF
PHOTOCHEMICA
L SMOG:
• Nitric oxide starts
a chain reaction.
• Reaction with
sunlight, water
vapor,
hydrocarbon,
results in over
100 secondary
pollutants.
ACID DEPOSITION
• Acidic deposition = deposition of acidic or acid-forming
pollutants from the atmosphere onto the Earth as acid rain,
acid fog, acid snow
• One type of atmospheric deposition
• Caused by reaction of pollutants like SO2 and NO with water,
oxygen, and oxidants resulting in sulfuric acid or nitric acid
• Can have wide-ranging detrimental effects on ecosystems
and the built environment
ACID DEPOSITION
• Acidic precipitation and dry
fallout both are corrosive and
damaging to biota
pH scale goes 0 to 14 (acid to base)
pH = - log [H+] in a solution.
Therefore each number higher on
the pH scale is 10X more basic
Acidic- produce H+ ions < pH 7
Basic- OH- (hydroxide ions) > pH 7
Neutral- pure water = pH 7
Normal rain slightly acidic-pH 6.4
Acid rain a pH < 5.5
ACID DEPOSITION
• Acid deposition is created by reactions in the atmosphere,
and can fall many miles from where pollution originated.
ACID DEPOSITION
• Acidity varies geographically. (Orange = more acidic)
Industrialized areas and regions downwind of them suffer
most. Areas with Limestone Bedrock are less acidic.
ACID
DEPOSITION
• It also eats away at statues and buildings.
ACID DEPOSITION
• Acid deposition has killed these conifer trees in the mountains
of North Carolina.
ACID DEPOSITION
• Acid
precipitation
harms soil and
plants, and alters
the chemistry of
ecosystems.
© Martin Kennedy, University of California-Riverside.
ACID DEPOSITION, PLANTS, AND
SOIL
 Nutrient
leaching
 Heavy metal
release
 Weakens trees
Fig. 20-11 p. 447
ACID DEPOSITION
• Following the 1970 Clean Air Act,
• Sulfur emissions have decreased due to:
• Technology (“scrubbers”) to clean
smokestacks
• Legislation and a market-based
emissions trading scheme
• But nitrate pollution has risen slightly, and
acidification is not being reversed as
many had hoped.
SOLUTIONS TO ACID DEPOSITION
Fig. 20-12 p. 448
SOURCES OF ACID RAIN
Natural:
a. Sulfur: Volcanoes, sea spray, microbial
b. Nitrogen oxides: lightening, forest fires,
microbial
Anthropogenic (human caused)
a. Sulfur oxides: coal burning plants, industry,
fossil fuels.
b. Nitrogen oxides: power plants, industrial fuel
combustion, transportation
c. Effect areas hundreds of miles from the source
of emissions, generally not the whole globe
d. Both sulfur oxides and nitrogen oxides are
primary components of acid rain.
INDOOR AIR POLLUTION
• Indoor air spaces generally have MORE
pollution than outdoor spaces.
• U.S. citizens spend 90% of time indoors.
• Countless consumer products and synthetic
chemicals kept indoors are used in our daily
lives.
UN estimate for world:
• 2.2 million deaths/year from indoor air pollution
• 0.5 million deaths/year from outdoor air
pollution
INDOOR AIR
POLLUTION
More disease from indoor
(orange) pollution than
outdoor (red)
In developing nations, indoor
cooking fires are common,
and a major health risk.
INDOOR AIR POLLUTION
• In developed nations, the 2 biggest threats seem to be:
• Cigarette smoke: lung cancer risk for smokers and
those inhaling secondhand smoke
• Radon: naturally occurring colorless, odorless gas;
radioactive—seeps up from ground and collects in
buildings; lung cancer risk
• Radon
varies in its
occurrence,
depending
on an
area’s
underlying
geology.
• It is best to
have your
home
tested for
radon.
RADON
INDOOR AIR POLLUTION RISKS IN
THE HOME
INDOOR AIR POLLUTANTS
1. Types: benzene, formaldehyde,
radon, cigarette smoke
2. Sources: off gassing from
furniture, rugs and building
materials, dry cleaning,
adhesives, cleaning fluids,
disinfectants, pesticides, heaters
3. Buildings with too many indoor
air pollutants are called “sick
buildings” because more than
20% of the people are sick due to
occupying the building.
SICK BUILDING SYNDROME ON
EPA WEBSITE
Indicators of SBS include:
Building occupants complain of symptoms associated with acute discomfort, e.g., headache; eye, nose, or throat
irritation; dry cough; dry or itchy skin; dizziness and nausea; difficulty in concentrating; fatigue; and sensitivity to
odors.
And most of the complainants report relief soon after leaving the building.
Causes of Sick Building Syndrome
• Inadequate ventilation
• Chemical contaminants from indoor sources
• Chemical contaminants from outdoor sources
• Biological contaminants
• Solutions to SBS:
pollutant source removal, increasing ventilation rates, air
cleaning/filtering, communication and education
OTHER INDOOR AIR POLLUTION
SOURCES
• Many VOCs pollute indoor air (plastics, oils, cleaning fluids,
adhesives, pesticides, building materials).
• Tiny living organisms (dust mites, animal dander, fungi, mold)
can produce indoor air pollution, causing allergies, asthma,
etc.
• When the cause of building-related illness is a mystery, the
illness is often called sick-building syndrome.
REDUCING INDOOR AIR POLLUTION
• Buy and use low-toxicity products
• Provide good ventilation
• Limit exposure to plastics, treated wood,
pesticides, cleansing fluids (put in garage, not
home)
• Test home for radon
• Test drinking water for lead from pipes
• In developing world, provide ventilation, install
clean-burning stoves, shift to gas
CONCLUSION
• Indoor air pollution is a potentially serious health
threat.
• Outdoor air pollution has been addressed more
effectively by government legislation and
regulation.
• There is much room for improvement in
reducing acidic deposition and photochemical
smog.
• This will continue to pose a challenge as lesswealthy nations industrialize.
REDUCING AIR POLLUTANT EMISSIONS
Best way = Conservation, just use less!
•
Reducing pollution from
transportation
Input Control (pollution prevention)
a.
Cleaner burning gasoline, remove
lead Pb which was used as an
antiknock substance
b. increased fuel efficiency
c. alternative modes of transportation
-Mass transit, Walking, Bicycling,
Electric vehicles
d. decrease the number of miles driven
REDUCING AIR POLLUTANT
EMISSIONS (INPUT CONTROL)
e. changes in land use decisions
f. catalytic converter- complete oxidation of hydrocarbons (VOCs) and
carbon monoxide to CO2 and H2O, makes for less the VOC and CO
pollutants
OUTPUT POLLUTION CONTROL
a)
Scrubbers on smoke stacks
b)
taller stacks to allow for cooling
and condensation
c) Coal washing-using large amount
of H2O to get rid of sulfur before
burning
d) Fluidized bed combustionproduces a waste ash that must
be disposed of
REDUCING POLLUTION FROM
ELECTRICITY PRODUCTION
• Input Control (pollution prevention)
A. Cleaner Burning Fuel by…
-Switching to low-sulfur coal
-Switching from coal to natural gas
-Switching from fossil fuel to renewable
energy source
B. Increase Energy Efficiency by…
-using insulation
- using more efficient appliances
OUTPUT CONTROL TECHNOLOGIES
Technological fixes to remove air pollutants
• Scrubbers are “liquid filters”: exhaust fumes through a
spray of H2O containing lime
• Also use elctrostatic precipators:
to precipitate out
SO2  CaSO3
• Required since 1977 in part due to Clean Air Act of
1970
AIR POLLUTIONS PROBLEMS AND
PROGRESS
• Incinerators: used to burn waste, used to do this in open air
with no exhaust filtering, very harmful
• Smelting: a form of metallurgy used in mining to heat/melt and
add electrolysis to molten ore to isolate the desired
mineral/metal
• Since removal of lead from car gasoline, levels of Pb found in
the environment, in animals and humans has been reduced
significantly.
• In 1960s biggest source of air pollution was factories and
industry. But since Clean Air Acts of 1970 and 1990, they have
been regulated and there has been a decrease in
atmospheric concentrations of VOCs, SOx, CO, NOx and
particulate matter (soot, smoke).
• Today biggest source of air pollution is transportation, vehicles.
• A few years ago, China surpassed the USA as being the
highest emitter of carbon dioxide. And the Asia/Pacific region
is a bigger carbon dioxide emitting region than North America.